Increased availability of sugar may be the single most important driver of the worldwide diabetes epidemic, a population-based study suggested.

Action Points

Note that this population level analysis demonstrates an independent association between sugar availability and diabetes prevalence.

Be aware that no individual-level data were available; significant residual confounding may exist.

Increased availability of sugar may be the single most important driver of the worldwide diabetes epidemic, a population-based study suggested.

For each 150-calorie daily increase per person in the availability of sugar, the prevalence of diabetes rose by 1.1% (95% CI 0.48 to 1.7, P<0.001), even after controlling for multiple potentially influential variables, according to Sanjay Basu, MD, PhD, of Stanford University in Stanford, Calif., and colleagues.

That quantity of calories approximates the content of one can of soda, they noted.

"Sugar availability appears to be uniquely correlated to diabetes prevalence independent of overweight and obesity prevalence rates, unlike other food types and total consumption, and independent of other changes in economic and social change such as urbanization, aging, changes to household income, sedentary lifestyles, and tobacco or alcohol use," the researchers wrote online in PLoS ONE.

While the rapid expansion in rates of obesity has generally been blamed for the doubling of rates of diabetes throughout the world in recent decades, obesity can't completely explain this trend.

"We found that obesity appeared to exacerbate, but not confound, the impact of sugar availability on diabetes prevalence, strengthening the argument for targeted public health approaches to excessive sugar consumption," they stated.

For example, certain nations such as France, Bangladesh, and Romania have low rates of obesity but high rates of diabetes, an observation that is not attributable to ethnicity or demographic factors, the researchers explained.

To explore the "controversial hypothesis" that sugar added to processed foods and soda could be the culprit, Basu and colleagues analyzed data from the United Nations Food and Agricultural Organization, which tracks supplies and marketing of various types of food across countries.

The hypothesis is biologically plausible, they argued, with hepatic metabolism of fructose leading to upregulation of lipogenesis, which, in turn, increases inflammation and insulin resistance in the liver.

Worldwide sugar supplies have grown from slightly under 220 calories for each person per day 50 years ago to more than 280 today, with the greatest increase having occurred during the most recent decade.

Basu and colleagues found that overall, the prevalence of diabetes increased by 27% between 2000 and 2010 in the 175 nations they included in their analysis.

In their statistical construct, certain factors other than sugar availability initially appeared important, such as gross domestic product and urbanization, but were no longer significant when obesity and food availability were included in the model.

Removing obesity from the model did not alter the effect size of sugar availability (β = 0.0081, P<0.001), which implied that the impact of sugar on rates of diabetes was not mediated by obesity, the researchers explained.

None of the other types of food -- fiber, cereal, oils, fruits, meat -- appeared to have any effect on diabetes prevalence.

Further analysis determined that in countries with "high sugar availability," meaning 300 calories per person each day, which is twice the recommended upper limit for adult males, each additional year led to a rise in diabetes prevalence of 0.053% (P<0.05).

Similarly, decreasing availability of sugar over time was associated with falling rates of diabetes, suggesting a causal relationship.

But the researchers pointed to a number of limitations to their analysis, including the use of population-level data and a lack of information about actual food consumption rather than availability.

They also had no information about different forms of sugar, such as high-fructose corn syrup.

In addition, their estimates of diabetes prevalence are likely to be low, because many patients are unaware of their disease.

Given these limitations, they cautioned "any of the findings we observe here are meant to be exploratory in nature, helping us to detect broad population patterns that deserve further testing through prospective longitudinal cohort studies in international settings."

Nonetheless, if sugar, rather than obesity, can be confirmed as the primary factor in diabetes prevalence, future public health efforts should be directed accordingly, they concluded.

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